During felling of timber with chain saws carried on harvester machines, it is common practice to spray the cut surface of the stump with a liquid such as an urea aolution to avoid fungal infections which can spread through the roots to neighboring standing trees. Guide bars for such liquid spray treatment are described in SE Patent No. 76 04765-3, SE Patent No. 76 11822-3, and U.S. Pat. No. 5,050,303.
The majority of guide bar designs for such treatment spray the liquid vertically from the lower surface of the guide bar through holes located near the line of symmetry, or from an elongated indentation in the surface. This means that in order to spray the entire cut surface of the stump the guide bar has to pass so far through the tree trunk that the holes reach the edge of the cut surface, which means that the cutting chain reaches around 10 mm past that edge. This means an excess time requirement, an excess demand for mobility of the guide bar and a risk that the tree trunk will settle down on the guide bar, preventing its return to the starting position, jamming or breaking the cutting chain or lifting the chain off the guide bar.
In another suggested design, the liquid is emitted through the chain groove to be spread over the stump surface by the chain links, with the disadvantage of degrading the chain lubrication oil and of wastefully spraying liquid outside the cut surface of the stump.
The present invention relates to a guide bar structure with a liquid spraying device comprising holes formed and located to disperse the liquid evenly in a direction more parallel to the surface of the guide bar to hit the cut surface in front of the holes in the guide bar structure, to save time and liquid, and to lower the risk of jamming.
A guide bar according to the invention has on its underside a plurality of holes connected to a channel within an interior of the guide bar for liquid supply. The guide bar is preferably reversible, having holes on both sides and two separate supply channels.
According to the present invention the guide bar is made from two side plates and one center plate joined by welding. The supply channels are cutouts in the center plate, and may be lined with thin-wailed tubes to avoid leakage. Near the machine attachment end of the guide bar, the channel is terminated at an opening in one side plate matching a supply opening in the clamping surface of the machine, through which liquid can be supplied from a pump and container on the machine.
According to the invention the spraying holes in the side plates are made as cutouts which are offset from the supply channels so far that less than half, preferably less than a fifth, of the area of the hole is overlapping the supply channel near its edge. This offset causes the liquid to emerge not as a narrow jet vertical to the sideplate surface, but with a velocity component along the sideplate surface, and with an angular spread to cover the cut surface evenly with a minimum amount of liquid.
Compared to the supply channels, the spraying holes are located closer to the leading edge of the guide bar, where the cutting part of the chain runs. This directs the liquid towards the chain, and each element of the cut surface is covered with liquid very soon after the passage of the chain and before the holes move past the element. This arrangement limits the requirement of angular mobility of the guide bar, and improves safety and productivity.